Electric motors



Oct. 17, 1961 E. RANSEEN 3,005,118

` ELECTRIC MOTORS Original Filed July 16, 1954 5 Sheets-Sheet 1 EMIL L. RANSEEMDECEASED BY AGNES J. RANSEEN,ADMINISTRATRIX Oct. 17, 1961 E. L.. FmNsEEN4 ELECTRIC MOTORS M D 2 wm t mmm m mmm w. v Vm Nil- .l .m WMM 0U. a L 5 .im ME w ES .v N..w d AM R x ilu. S E N G A m 5 m lll o Gv I|l L. I mq.. l d B F nw Iii( 1 T m am ,w HR n Pw M Z OC m ZTA. E i r D 0 Illa i. ,'Afe u 7l m Oct. 17, 1961 E. l.. RANsr-:EN 3,005,118

ELECTRIC Mo'roRs Original Filed July 16, 1954 5 Sheets-Sheet 3 7S 76 'T 'T8 Fuel Oct. 17, 1961 E. L.. RANsEEN 3,005,118

ELECTRIC MOTORS Original Filed July 16, 1954 5 Sheets-Sheet 4 Las INVENTOR.

/ 29?;2" EMIL L. RANSEEMDECEASED Atries J. RANSEEMADMINISTRATRIX ol v'w .L

E. L. RANSEEN ELECTRIC MOTORS Oct. 17, 1961 5 Sheets-Sheet 5 Original Filed July 16, 1954 Fael?.

INvEN'roR EMIL L. RANSEEN,DECEASED, BY AGNES J. RANSEEN,ADMINISTRATRIX Unitey States arent O ELECTRIC MOTORS t Emil L. Ranseen, deceased, late of Chicago, Ill., by Agnes J. Ranseen, exeeutrix, Chicago, Ill., assigner, by decree of distribution, to said Agnes J. Ranseen Original application July 16, 1954, Ser. No. 443,798,

now Patent No. 2,797,346, dated July 25, 1957. Divided and this application June 20, 1.957, Ser. No.

16 Claims; (Cl. S10-49) This invention relates to improvements in electric motors of the impulse type. By that term is meant motors which are of construction such that their operation is produced by successive impulses of current delivered to the motor either in regular timing or at various pauses between successive impulses. Such motors are also of such construction that each impulse of current delivered to the motor produces a known and pre-determined angular advance of the rotor, under motor operation.

One feature of the invention concerns itself with the provision of a construction of stepping motors of that type in which the rotor teeth extend radially into the axial alignment with the ystator teeth so that special pro vision must be made in the structure of the device to -enable assembly of the successive stator and rotor ele'- ments endwise and in proper sequence of such assembly, thus avoiding the need of splitting the rotor and stator elements on a plane or planes parallel to the shaft.

Other` features concern themselves with various means to produce proper sequential delivery of the pulses of current to the several stator exciting coils. In this connection there is disclosed several forms ofv commutation devices driven by the rotor itself, so that as suchy rotor rotates the incoming pulses or steady current supply are or is delivered to the exciting coils in the proper sequence. These improvements also include means to vary or adjust the phasing of the pulses delivered to the several stator coils for various purposes and results. i

A further feature of the invention relates to the provision for controlling the rate of magnetization of demagnetization of the stator coils for various reasons and purposes related to thefunctioning of the motor. In this connection there is disclosed capacitor and resistor arrangements by Which the decay time of the magnetization can be brought to an optimum condition, taking account of the rate at which the pulses are required yfor motor operation.

Still another feature relates to the provision of flexible clutchlmeans intermediate between the rotor shaft of the motor and a driven load, such as a load of large mass of which the momentum is large, to enable bringing such large mass load into speed, such mass being so large that a considerable time must elapse before the torque deliveredtby the stepping motor can bring such mass into intended rate of movement. There is a special relation between the effects producedy by such flexible clutch when interposed between a stepping motor drive and the load, as differentiated from bringing such load into motion by use of'a conventional substantially steady torque motor.

A further feature of the inventionrelates to the provision of special means to lock the rotor against rotation at conclusion of a series of stepping impulse produced advances. In this connection provision has been made for retaining the energizing current on that one of the several stator coils which will produce the locking at the desired pulse, or at conclusion of response to a pre-determined number of delivered pulses. Such retention of the current onV such stator coil will strongly lock the rotor in the desired position. y

normal conditions of .moansy Patented Oct. 17, 1961 lCCV,

Other` objects and uses of the invention will appear from a detailed description of the same, which consists in the features Yof construction and combinations of parts hereinafter described and claimed. f

Inthe drawings:

FIGURE 1 shows a perspective view of one form of motor embodying various of the features of invention, this ligure being in partial section;

FIGURE 2 shows a longitudinal section corresponding to FIGURE l, but in blasted form;

FIGURE 3 shows aface view of a modified form of rotor polar element; v i n FIGURE 4 shows a commutator unit which may be either manually driven or driven bythe rotor for control of energization of the stator coils of a motor embodying features of the present invention;

' FEGURE 5 shows schematically the three coils of a typical three section stator element of a motor embodying features of the present invention, and with said coils connected together in delta connection, for supply of three phase A.C. to said coils whenthe motor is t0 be operated by such a current supply; g

FIGUREG shows schematically a modified arrangement of stator coils of a motor embodying features of the ypresent invention, in which modification each stator coil is subdivided into two sections, and each such section isrcentrallytapped, all such coil elements being ring or delta connected together, together with a commutator suitable for combinationrwith such a sectionalized coil arrangement; t t

FiGURE 7 shows a fragmentary, perspective view of a portion of the stator element showing how the blocks which sub-divide the gap between the two poles kof the stator may be convenientlysupported;

FIGURE 8 shows a fragmentary perspective `view of a portion of the stator element showing how laminations of said statorfe'lernent may be conveniently supported in a suitable structure to establish a portion of the true polar element; y

FIGURE 9 shows a fragmentary perspective view of a portion of the rotor element showing how laminations may be supported in the periphery of a rotor plate;

FIGURE l0 shows a fragmentary perspective view of a portion of the stator element showing how laminations of said stator element may be conveniently supported in a suitable structure to establish the stator formation between two of the coils, and this figure may be considered as'being complementary to the showing of FIGURE 8;

FIGURE l1 shows a fragmentary perspective view of a modification of the embodiment shown in FIGURE 2;

FIGURE l2 shows a longitudinal view partly in section, of another modified embodiment of the features of the present invention, in rwhich modification the stator is located within the rotor;

FIGURE 13 shows a fragmentary half section longitudinally through another modified embodiment of the invention; i

FEGURE 14 shows a fragmentary cross-section` taken on the line` 4--14 of FIGURE 13, looking in the direction of the arrows;

FlGURE 15 is a schematic showing of a motor embodying features of the present invention with its motor shaft Ycoupled to a high inertia load, such as the table of a machine tool, such coupling being effected through the medium of a flexible coupling of construction such as to allowr for a small angular displacement of the; drivsuch ing end without corresponding displacement of the driven end;

FIGURE 16 shows more or less schematically, and in perspective, some of the commutating elements by which a motor may be controlled for various conditions of operation; and the elements shown in this figure will be better understood by reference to FIGURE 2l which is a schematic wiring diagram to be read in connection with FIGURE 16; e

FIGURE 17 shows, more or less schematically, a motor embodying features of the present invention, and provided with a commutator arrangement for control of current delivery to the several stator coils in proper sequence, and this gure also shows a friction brake interposed between the rotor and the driven load;

FIGURE 18 shows schematically a simple circuit arrangement for use in connection with the motor arrangement of FIGURE 17, including the commutation elements thereof;

FIGURE 19 shows a longitudinal fragmentary section through the commutator end of a motor embodying the features shown in FIGURE 16, this gure showing the commutation arrangements for one of the three stator coils;

FIGURE 20 shows an end view corresponding to FIGURE 19;

FIGURE 2l shows a schematic wiring diagram of the stator coils, the commutation elements, and the switching gear of the arrangement shown in fragmentary form in FIGURE 16 and also shown in FIGURES 19 and 20;

FIGURE 22 shows a portion of the commutating elements for a three stator coil motor, in which commutating elements use is made of a rotor shaft driven cam element and co-operating switch elements such as microswitches;

FIGURE 23 shows a schematic wiring diagram including the commutation elements shown in FIGURE 22; and

FIGURE 24 shows schematically a single stator coil and capacitors (and a resistor) connected across such coil, being a`modified arrangement as compared to other coil arrangements also illustrated herein, such modifications enabling operation with a smaller loss of energy than will occur with previously illustrated arrangements.

Referring first to FIGURES 1 and 2, there is therein shown a typical motor construction embodying certain of the features of novelty herein disclosed. The motor shown in these two gures, and elsewhere, includes three stator elements and corresponding rotor elements, and is so devised that rotor rotation may be produced in either direction. This construction includes an energizing coil -for each stator element, and the teeth of the several stator and rotor elements are so related and positioned that by energizing the stator coils in succession the steps of rotor advancement will be sequential, three steps comprising a group, and each stator coil being energized at its proper sequential position in such group. By energizing the three stator coils in either sequence, such as A, B, and C or A, C, and B, the direction of rotation can be determined. Various other features and functions will appear as the motor construction is detailed.

Herein disclosed are several means and arrangements for controlling the delivery of the impulses to the several coils. These are now disclosed as follows:

The current impulses must be delivered to the several stator coils in an orderly and predetermined sequence to effect rotor rotation in either direction. The successive impulses may be delivered to the stator coils at equal and predetermined intervals, or at unequal intervals, but in that order or sequence which corresponds to a desired direction of rotation. Or, as may sometimes happen, the impulses may come in what may be termed a two directional sequence, some of the impulses corresponding to rotation in one direction, and some to rotation in contrary direction. This mght be true, for example, in an installation in which an algebraic sum of positive and negative digits was to be obtained, including therefore some impulses corresponding to forward rotation, and some corresponding to reverse rotation.

It is also to be noted that the impulses may be delivered to the stator coils under such controls as suggested above, either with the origination of the impulses at some remote location, and by an impulse generator completely independent of the motor itself, or said impulses may be created by the motor itself by means' of some element or unit rotating in harmony with and under control of, the advancements of the rotor itself. Such an arrangement might take the form of a commutation element physically connected to and driven by the rotor, and provided with means and contacts whereby the connections to the stator coils would be effected in the manner and the sequence desired or required.

In FIGURE 5 there are shown the three stator coils as A, B and C, corresponding to the three coils of FIGURES 1 and 2, for example. These coils are shown in delta connection, for simplicity, and the three delta terminals are shown at 188, 189 and 190. These are brought to the switch contacts 191, 192 and 193 by which delivery of the three phase current to the three motor terminals in selected order is effected.

In FIGURE 15 there is shown another embodiment of a three phase current supply to the motor coils, and

in this case there is illustrated a typical industrial application of the motor to a service for which it may be well adapted. In this case the motor is designated generally by the numeral 194, its stator coils by the numerals 195, 196 and 197, and the rotor shaft by the numeral 198. The coils are conveniently delta connected, their coil terminals being shown at 198, 199 and 200, respectively. The reversing control switch 201 is illustrated, being connected in conventional manner for reversal of two of the supply phases in order to effect reversal of rotor rotation.

The motor illustrated in this ligure is provided with a large number of stator and rotor teeth, so that the angular advance produced by each current impulse is correspondingly small. Furthermore, if desired, this motor may be provided with the multiple tooth arrangement such as shown in FIGURES 13 and 14, so that even when using such large number of teeth per revolution and small angular advancement per step a high torque may be developed.

In FIGURE 15 the work to which this motor is connected Vcomprises such an element Vas the machine tool table 202 riding on the ways 203 (only one of which is shown). The table is provided with the rack bar 204 which is engaged by the pinion 20S carried by the stub shaft 206. The coupling 207 connects the motor shaft 198 to this stub shaft 206 so that slight angular displacements may occur between the motor shaft and said stub shaft, but without permanent angular displacement of the two shafts with respect to each other. Thus, assuming that the work has a large mass and correspondingly large inertia, as the motor coil is subjected to a current impulse its advancement may immediately commence, the coupling yielding slightly to allow the rotor to get under way and develop torque and build up the force acting to accelerate the work, and the movement of the work may thus be increased While preventing any stalling of the rotor to occur. When the work has thus been accelerated to speed the delivery of the impulses to the stator coils, with the workunder movement, will occur without material angular displacements occurring within the coupling itself. This general operation has been described on the assumption that the current supply to the motor is a conventional three phase supply. It Will be evident, however, that similar advantages produced by the Yfeatures of motor construction hereinbefore disclosed which enable production of high torques combined with relatively small angular advancements per impulse may be made available even when the impulses are delivered to the stator coils otherwise than as conventional three phase 7 sub-section, numbered 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242 and 243. The center points of the sub-sections are connected to the alternate commutator bars, as follows; AAA to 232; AA to 2314; BBB to.236; BB to 238; CCC to 240; and CC to 242; by the leads 244, 245,246, 247, 248 and 2149, respectively. VThe ring leads 226, 227 and 228 are connected to the commutator bars 235, 239 and 243 by the leads 250, 251` and 252, respectively, and the ring leads 229, 230 and 2311 are connected tothe commutator bars 233, 237 and 241 by the leads 253, 254 and 255, respectively. For convenience of showing there are included the dashed lines at the sides of the leads 250, 251 and 252 to emphasize the division locations between the successive coil units A, B and C-Q I l The commutator bars subtend equal angulal embracements, being 30 degrees each, corresponding to the sub sections. There are indicated the two slip rings 256 and 257 which rotate with the rotor element. The brushes 258 and 259 are connected to said slip rings by the leads 260 and 261, respectively, said brushes also being carried by and rotating with the rotor element. A source of D.C. is shown in the form of the battery 262. The terminals of this battery connect to the brushes 263 and 264 by the leads 265 and 266, respectively, said brushes bearing against the slip rings 256 and-257, respectively. Thus current is supplied through the stationary brushes 263y and 264 and the rotating slip rings 256 and 257, to the rotating brushes 258 and 259 to the stationary commutator bars, and from them to the stationary stator exciting coil sections. lConveniently the brushes 258 and 259 may be carried by a carrier which can be rocked about the rotor axis to thereby adjust the angular positions of the brushes as a pair, with respect to the angular positions of the rotor teeth, so as to ensure a proper and desired relation between the rotor teeth and the commutation points. The mechanical means to enable such angular adjustments are not herein illustrated since they may be of conventional form.

' .The structural details of the coil elements have not been illustrated in FIGURE 6. However, by reference to FIG- URE 1 it willbe apparent that each of the main coils -A, B andy C of FIGURE l may be divided into two sections by either a horizontal or a vert-ical plane of division, thus providing the two coil sections within a common annular space, and corresponding to the sections AA and AAA of FIGURE l, for example, in place of the single unit A of FIGURE 1. Then the proper taps and connections may be provided to the coil sections so provided. The commutator and brush and slip ring elements may also be provided at one end of the motor unit according to well understood and conventional practice.

' It will be seen that by such subdivisions of the main exciting coils as disclosed in FIGURE 6 it is possible to obtain an operation closely simulating the operating effects of supply of wave form currents such as shown in FIGURE 5, for example. Thus very smooth torque effects will be produced, but in combination with the novel functions herein disclosed. It is stated that the shaft 2081shown in FIGURE 4 may comprise the motor shaft itself, so that with the disclosures of that figure it is possible to obtain self-commutation or proper progressive excitation of the various stator coils. In FIGURE 4 there is also shown the button Q67 carried by saidshaft 208 so that, when the unit of FIGURE 4 is not physically connected to the motor itself, the rotations and control of the shafts 208 and 211 may be effected manually or otherwise, producing the desired current impulses which will then be correctly delivered to the stator coils and in proper sequence and controlled timing. Thus a remote control of the excitations of the stator coils will be produced, the several coils A, B andy C. of FIGURE 4v being located in the motor and at a distance from the unit shown in FIGURE 4. This is also true of the arrangement shown in FIGURE 6.

Reference may now be had to FIGURES 17 and 18 in which there is shown another embodiment similar in general to that shown in FIGURE 4. In the case lof FIGURES 17 and 18 the motor is generally designated as 268g, and the various gear elements, commutator and brush unit, and similar parts are designated by numerals generally the same as used in FIGURE 4. However, in the present case there is shown the commutator as provided with double the number of segments shown in FIGURE 4, being six in number; and there are shown these segments 268, 269, 270, 271, 272 and 273 as cross connected in opposite pairs by the leads 274, 275 and 276. These cross connections are then connected to the free ends of the stator exciting coils A,,B and C by the leads 277, 278 and 279, respectively. The other ends of the coils are then connected to the common lead 280, comprising one side of the source of current. The other side of such source of current connects by the lead 281 to the brush 282 which bears against the commutator. The current is thus supplied to the several stator lcoils in proper sequence. In this arrangement the commutator segments are twice the number of the motor sections, so that the multiple heretofore mentioned is two. v

In FIGURE 17 there is shown the commutatorshaft 220 as provided with the phasing handle 283 so that the phasing vof the commutator bars may be readily adjusted from time to time by a simple adjustment. It will be noted that by such phasing adjustment from one operating position to and through the neutral brush position, to an operating position -at the opposite side of such neutral position, it is possible to actually reverse the motor operation. Furthermore, by adjustment of the phasing it is possible to produce operations in which the excitations of the several stator coils are carried beyond the rotor positions of exact registration of rotor teeth with the stator teeth,v so that overlaps are produced in the torque forces developed on the rotor. If the phasing setting of such comutator shaft be such that current is cut oi from one coil at the condition of exact registry of the rotor teeth of such motor section with the stator teeth of such motor section, with simultaneous excitation of the stator coil next in the sequence, it is evident that no dragging effect will be produced by an overlapping of the excitation of the earlier coil after the position of exact registry of the teeth has occurred. By shifting the handle 283, however, far enough, such an overstaying operation may be produced, with corresponding hold-back on the rotor element. Such an'operation may be desired for certain operations.

Referring again to FIGURE 18 there is therein shown a capacitor 284 and resistor 285 connected in series shunt with each of the stator coils A, B and C. By selection of proper impedance values for these capacitors and resistors, in comparison to the impedance effects of the so bridged excitation coils, it is possible to produce time constants for the excitations and de-magnetizations of the main coils, to ensure either fast or slow de-rnagnetization responses of the magnetic eiects produced between the rotor and stator teeth. Thereby it is possible to ensure either very fast responses, corresponding to ability to produce very quick rotor advancements, or the repenses may be substantially slowed down, thus producing a correspondingly slow'rotor response to each exictation or signal. The inclusion of the resistor 285 inseries with the capacitor and such series being bridged across the stator coil, the discharging of the capacitor may be substantially slowed down so that the demagnetization of the stator poles may be correspondingly delayed. Thus it is possible to produce a combination in which the magnetization of the stator teeth will occur very rapidly upon closing the circuit to the coil for such teeth, followed by a retention of full magnetization as long as such circuit remains closed, followed by a slowed decay of the magnetization when the circuit to such coil is opened'.

92. Thereby the current may be sustained in the coil even after the circuit is opened, thus sustaining the magnetization to produce an overlap of the excitation of the coil of the next section or to approach the instant at which such next section excitation will occur.

It will now be illuminating to consider some modes of operation of the motor of FIGURE 17 with the circuit arrangements of FIGURE 18. First let us considerl that the motor is under heavy load bothy frictional and inertial. Now if the input terminals are connected to direct' current andfwith the phasing handle 283 in the proper position, the motor will slowly accelerate in a given direction. The motor will continue to accelerate until the impedance of the coils will not allow enough of a current rise in a motor section when the teeth are in the best relation to exert suilicient torce for further acceleration. By adjusting the phasing handle so that the commutator will allow current to be switched to the coils so that the current will have time to rise to a suicient maximum while the rotor and stator vteeth are at an optimum relation will also further increase acceleration.

If now the phasing handle 283 is further adjusted so that the flux becomes a maximum as the rotor teeth are leaving the stator teeth of the successive sections, a braking action will take place and the rotor will be rapidly decelerated If the kphasing handle is left in this position, the motor will go through the stationary position and begin to accelerate in a reverse direction. If desired, however, a further adjustment of the phasing handle when the rotor is substantially stationary will cause the commutator to switch current to the section where the stator and rotor teeth are in alignment and the rotor will lock in such position. In these operations of the motor the capacitors will serve primarily in an anti-sparking capacity or function.

'The motor of FIGURE 17 may also be operated by connecting the input terminals to a source of pulses -of current. The motor in this case advances one step for each pulse, the phasing lever being properly set. If the 'motor is intended for counting pulses, there 'being little or no external load on the motor, it may be desirable to improve its manner of operation by adding an appropriate frictional load to the motor by means of the frictional clutch 317 (shown in FIGURE 17). This comprises the brake disk 318 carried by the stationary stud 319 and screw-threaded on said stud as shown in FIGURE 17 so that the frictional drag may be adjusted or calibrated, together with the rotor shaft driven friction `disk 320 which is spring pressed against the kdisk 318 by the adjustable spring 321. 1

Without such a frictional load, When the rotor has been accelerated by the current pulse, thev inertia can carry the rotor considerably beyond the alignment of stator teeth and rotor teeth. The duration of the current must therefore be longer so that the rotor does not continue to rotate and is brought back to the proper position for the next pulse. With the frictional load, however, the duration of the pulsey may be increased, and therefore the rate of counting may ber increased, the frictional load being adjusted to a value which is optimum to give this result. n i

For a counting operation the capacitors 4may perform an additional function to that of preventing sparking of the commutator contacts. With the capacitors of correct capacity the duration of the input pulses need tbe only long enough to charge the capacitor in circuit at each pulse. 'Ihe current from the capacitor can then be sufficient to ensure completion of the corresponding step of the rotor. Thus pulses of short duration can be counted as well as pulses of longer duration.

The speed at which the motor lmay count depends on the rapidity with which the rotor can make a step. The steps can be exceedingly rapid when the rotor has a low inertia and a small angular movement per step. Although the duration of a pulse to make the motor advance one step may be exceedingly short when use is made of the capacitors, the current delivery through the coil must be of such rshort duration that -it has yceased when the movement yof the rotor has brought the oontactor elements to their next position of circuitry. When the next capacitor is charged, 'the rotor will advance another step. In line with the foregoing, if direct current is applied to the motor under the foregoing conditions, the motor will advance step-by-step at a substantially constant rate. This rate can be controlled by the size Aof the capacitors used, the larger .capacitors being associated with the vlower rates. f

The 'control arrangements so far described serve rto supply to the stator coils current impulses of regularly recurring kind. It is to be noted, however, that various important uses of motors embodying thefeatures of invention include the delivery of single pulses or groups of pulses, to the coils, to thereby produce corresponding rotor advances for such purposes as counting, and the like. There are Vnow described certain embodiments whereby the impulses may be severally controlled from a distance, as during the counting of digits, recording various steps of an operation, and like purposes. References may be had to FIGURES 16, 19, 20 and 2l kdisclosing one suchfembodiment.

In FIGURE 21 there are shown three stator coils Aff B and C (together with the capacitors and resistors such as shown-in FIGURE 18 bridged across each kstator coil). There are also shown, schematically, the leads 286, 287 and 288 extending leftward from the free ends of these coils, and `the common return lead 289 connected to the right-hand ends of the coils. The lead -289 connects to one side of a source of DJC. current, such as the battery 290. Each of the leads 286, 287 and 2 88 may be considered as representing a development of a circular conductor, with the ten contacts 291 connected to each of such circular or ring shaped conductors. For clarity these contacts '291 are designated as 291, 291i), and 291 rfor the three conductors 286, 287, and 288, respectively.

In this iigure there are also shown the movable sets of contacts k292, 293 and 294 for the contacts 291 of the three sets connected to 'the three conductors 286, 287 .and 288. For clarity these contacts 292, 293 and 294 are shown with the suffixes 51, b and c, corresponding tothe conductors `286, 287 and 288, respectively. The three contacts of each of these sets are carried by a common carrier which may move from station to station along the conductors 286, 287 and 288 (actually moving circularly since the conductors 286, 287 and 288 actually comprise circular conductors as above explained. These carriers actually rotate in harmony with the rotor rotations). The contacts 292e, 292b and 292C, yare connected to a common lead 295, the contacts 293, 293h and 293, are connected to a'common lead 296, and the contacts 294, 294b and 294C, are connected to a common lead 297. The free end of :the source of current, the battery, is connected by the lead 298 to the three switch elements 299, 300 and 301, respectively, which control connection of the lead 298 with the three leads 295, 2.96 and 297, respectively.

Examination of FIGURE 2l will show that the contacts y291 are vertically aligned with each other in sets, each set including a contact to each ofthe leads 286,287 and 288. Also, that the movable contacts 292 are stepped rightwardly, counting downwardly from the lead 286 to .the lead 287, to the lead 288; that the contacts 293 are also stepped rightwardly, counting downwardly from the lead l286 to the lead `287, to the lead 288; and that the contacts 294 are also stepped rightwardly, counting downwardly from the lead 286 to the lead 287, to the lead 288. These steppings or spacings are such that when the contact 292 is -engaged with one of the contacts 291%, ythe othercontacts 293a and 294a are set back kone-third of the spacing between the successive contacts 2911, and two-thirds of such spacing, respectively, so that rightward movement of the carrier will first open the contact 292 from one of the contacts 291e, with which it was engaged,

then will bring the contact 293a into engagement with one of the contacts 291e, then will open the contact 293a from such contact 291e, and inally will bring the contact 294a into engagement with one of the contacts 291% then will open the contact 294YL from such contact 291B. Examination of this figure will also show that similar contacting engagement and disengagement will occur for the other carrier contacts b and c in regular order through the groups.

i In the position shown in FIGURE 21 the contact 292a is seen to be engaged with the contact 291e, the contact 293D with the contact 291D, and the contact 294c with the contact 2910. All of the switches 299, 300 and 301 are however, open. Accordingly, none of the circuits of the coils A, B and C is actually closed. Reference will now be made to FIGURE 1 to complete the description and understanding of the operation now to be described. In FIGURE l it is seen that the left-hand rotor section is in such position that upon energizing the stator coil A the rotor will be drawn clockwise to bring the teeth of such left-hand rotor section into complete registry with the corresponding stator teeth. Accordingly, by closing the switch 299 (of FIGURE 21), with energization of the stator coil A, the rotor will be moved substantially one-.third of a tooth spacing to bring the lefthand rotor section teeth into complete registry with the corresponding stator teeth; and at the same time the rotor teeth of the central section will move clockwise away from the stator teeth with which they have been registered, and the rotor teeth of the right-hand section C will move clockwise into position preparatory to being drawn into registry with the next set of stator teeth of the section C under proper excitation conditions. Therefore, if after having closed the switch 299 just long enough to cause such stepping advancement of the rotor, such switch now be opened and then the switch 299 be again closed a further forward step of the rotor will occur since such second closing of the switch 299 will now energize the stator coil C (the contacts 292, 293c and 294c having been advanced rightwardly by the first operation). Finally a third such closing of the switch 299 will result in a third clockwise step of the rotor, the carrier having been shifted rightwardly a still further step, thus, successive closings and openings of the switch 299 will result in successive clockwise steppings of the rotor. It should be here noted that in case the switch 299 should be held in its closed position the rotor will continue to step rightwardly or clockwise by steps at a rate dependent on various of the rate affecting conditions which have been previously discussed hereinbefore.

Further exploration of the operations of this arrangement -will show that successive closings and openings of the switch 301 will result in successive counterclockwise steppings of the rotor element. Also, that closing of the switch 300 will result merely in exciting the stator coil B at which motor section the rotor teeth are completely registered with the stator poles, thus Vproducing no torque action, and merely serving to magnetically lock the rotor in its then position.

It will be understood that the switches 299, 300 and 301 may be located at any convenient control position, and may be operated by any suitable device with which the motor is to be combined and operated.

In FIGURES 16, 19` and 20 there is shown in fragmentary form a mechanical structure capable of eiectuating the proper con-tact movements to enable functioning according to the operations just explained in connection with the description of FIGURE 21. The rotor shaft 302 is extended suiiciently to carry the insulating sleeve 303 on which are mounted the three slip rings 295D, 296b and 2971. The source of current-the battery 290 in the present case-is shown in FIGURE 16, with one terminal connected to the lead 298. Also, the three switches 299, 300 and 301 are shown in FIGURE 16. The brushes 295g, 296EL and 297a of FIGURE 16 correspond to portions of the leads 295, 296 and 297 of FIGURE 21; These brushes engage the slip rings 2959, 296b and 297", which slip rings in turn connect to the leads 295C, 296c and 297c extending inwardly through the shaft (which is provided with a suitable bore to accommodate said leads). The other terminal of the battery connects to the lead 289. For simplicity of illustration and to avoid confusion there are shown only the stator coil A in this ligure, and there are also shown only the contacts needed to control that coils excitation.

The arcuate segment 286a simulates a portion of the lead 286 shown in FIGURE 21. Said segment carries the inwardly extending contact lingers 291, corresponding to the contacts 291a of FIGURE 21. A disk of insulation material 304 is carried by the shaft of the rotor; and the three contacts fingers 29235, 293aa and 29488, extend outwardly from such disk within a plane normal to the axis of rotation, and substantially in line with the contacts 29129. These fingers 292m, 293aa and 294aua are spaced with respect to each other according to the principles already explained with respect to the spacing of the contacts 292, 293 and 294 with respect to each other and with respect to the contacts 291am of the ring element 286B. It will be understood that in actuality the other stator coils B and C would also be connected to the lead 289, that two other ring shaped conductors similar to the conductor 286 would be provided with their inwardly extending fingers, and that two other sets of the fingers 292%, 293aa and 294ea would be provided, connected to the leads 295C, 296c and 297, respectively. Thus the schematic showing of FIGURE 21 would be duplicated in a physical structure of which FIGURE 2l is but a portion. It is thus unnecessary to describe the operation of the showing of FIGURE 16 further.

FIGURES 19 and 20 are a fragmentary longitudinal section through the arrangement shown in FIGURE 16, and a fragmentary cross-section corresponding thereto. Their description in detail is deemed unnecessary in view of -what has already been explained.

It is remarkedthat in the showing of FIGURE 21 there are included the capacitor and resistor combinations bridged across the several stator coils, according to the principles described in connection with the showing of FIGURE 18.

In FIGURES 22 and 23 there is shown another arrangement for effecting commutation of the current impulses to the several stator coils in proper sequence. In this case there is shown'the rotor shaft 305 carrying the disk of insulating material 306 at a location outside of the stator housing. The three microswitches 307, 308 and 309 are mounted to a convenient element around the disk 306. These microswitches are provided with the small buttons which are engaged by an element to reverse their biased spring leaf contacts according to conventional designs. There are not shown these details in FIGURES 22 and 23, beyond showing the buttons 310 projecting slightly beyond the switch housings. The disk 306`is provided with dwells 311, 312 and 313 around its periphery, and other dwells not numbered are also shown. The microswitches are set at positions around the disk such that the several microswitches will be actuated in proper sequence to product the desired sequence and timing of the excitations of the stator coils. In view of the detailed descriptions already given it is deemed unnecessary to further describe the present arrangement.

In FIGURE 24 there is shown another modified means to produce desired time delay constants in the operations 'of the stator coils. In this case there are shown the capacitor 314 bridged across a portion of the coil, and another capacitor 315 and resistor 316 in series bridged across the entire body of the coil. The effects of such an arrangement will be readily understood by one skilled in the arts.

Reference has-been made to the use of laminated pole and tooth constructions for reduction of eddy current sposti-s losses and other well understood advantages.`y Such type of construction will generally be found advantageous for frequencies of substantially 400 c.p`.s. For very' high kfrequencies it may be found desirable to use polar and tooth constructionsformed of sinterednely granular magnetic material highly compacted' by large pressures, as is well understood in the magnetic arts. Such forms of construction may be found desirable for use with frequencies of the order of 1000 c.p.s. and higher.

Attention is called to the fact that the embodiment Shown in FIGURES 13 and l4 which incorporates the axially aligned type one features combined with the subgap features, also presen-ts the further feature that the body portions of the two statortooth carriers for the single sectionk illustrated in such figuresk are yformed of magnetic material, the exciting coils being set into such stator body portions. Then the hub portions of such magneti'c material body elements are also of magnetic material but separated from each other to accommodate the hub portion 169 of the corresponding rotor element. This rotor hub portion is also of magnetic material, and small gaps are provided between the rotor hub vportion and the proximate stator hub portions. These gaps may be made small since there is no possibility of lateral deflections of the rotor hub portion which is locked t'o the shaft and such shaft may be readily held against endwise shifts with respect to the stator or body of the motor. Accordingly, with this combined arrangement it is possible to secure the benefits of the axially aligned stator and rotor teeth feature, together with the benefits of large radius of the rotor teeth with corresponding torque benet, 'and the further benefit ofl bringing the exciting coils to small 'radius values for specified ampere turns. These features may or may not be further combined with the benefits of the sub-gap feature which is more completely disclosed i'n said parent application, Serial No. 443,7 98, now Patent No. 2,797,346, of which case the present is a divisional case thereof.

It is claimed:

l; In an electric motor, the combination of stator and rotor elements', means to journal said elements co-axially with` respect to each other, the stator element including a plurality of sections not less than three spaced in succession axially of the motor, each stator element including a plurality of stator poles spaced equidistant around' the axis of the motor and at the same radius from said axis, the rotor element including a plurality of sections equal to the number of stator sections, each rotor section including a plurali-ty of teeth spaced equidistant around the axis of the motor and at the same radius from said axis, the nurnber of rotor teeth of each section being equal to the nutmber of stator poles of such section, the teeth of each rotor section ybei-ng simultaneously in full registry with the poles of the companion stator section for each angularadvance of the rotor equal to 360 divided by the number of rotor teeth of such section, and the teeth of .the several rotor sections being successively in full registry with the poles of the companion stator sections with progress of such full registry of the rotor teeth and companion stator poles of the sections in successive cycles of such full registry conditions of the sections, magnetizing coils for the several sections7 each coil when 'energized generating a magnetomotive force producing ux flow between'allof the poles of the corresponding stator section and all of the teeth of such rotor section, together with commutation means to electrically energize the magnetzing coils in succession, said commutation means including a commutator having a number of commutation elements equal to a full multiple-of the number of motor sections, connections between the commutation elements and the coils in a progression around the commutator corresponding to cyclic progress of energization of the motor sections which have full registry of their rotor teeth and stator poles, and with one cycle of electriiication of the stator coils `for each cyclic electrification of rthe commutation elements, and means to electrify the commutation elements in said cycle of progress.

g means which electrifies the commutation elements, f

2. ln an electric motor, the combination of stator and rotor elements, means to journal saidv elements co^axially with respect to each other, the stator elementV including a plurality ofv sections not less than three spaced in succession axially of Vthe motor, each stator element including a' plurality of stator poles spaced equidistant around the axis of the motor and at the same radius from' said axis, the 'rotor velement including a plurality of sectionsA equal to the number of stator sec-tions, each rotor section including a plurality of teeth spaced equid'istant around the axis o-f the rotorand at the same radius from said axis, the numbery of rotor teeth of each ysection being equal to the number of statorl poles of such section, the teeth of each rotor being simultaneously in full registry with the poles of the" companion stator section for each angular advance of the rotor equal to 360 divided by the number of rotor teeth of such section, and the teeth of the severa-l rotor sections beingA successively in `full registry with the poles of the companion stator sect-ions `with progress of such full registry of 'the' rotor teeth and companion stator poles' of the sections in successive cycles of such full registry conditions ofthe sections, magnet-izing coils furthe-several sections, eachcoil when energized generating a magnet-emotive force producing ilux ilow between all of the poles of the corresponding Istator section and all Vof 'the' teeth of such rotor section, together with commutation means to electrically energize the magnetizing coils in succession, said commutation means including axcommutator having a number of commutation elements equal to a full multi-ple of the number of motor sections,

connections between the commutation elements `and the coils in a progression around the Vcom-mut-ator corresponding to cyclic progressv ofl energization ofthe motor sections which have full registry of their' rotor teeth and stator poles, andv with4 one cycle of electriiication of the stator coils for each cyclic `electri'iication of the commutation elements, and means -to electrify the commutation elcments in saidcycle of progress, together withA operative connections between the rotor and the meanswhich electriiies the commutation elements in said cycle of progress, said operative means being constituted to electrify the commutation elements in a cyclic recurrance with electrilication of each stator magnetizing coifl anumber of times equal to the num-ber of stator teeth ineach section, duirug each full rotation of the rotor.

3. Means as delined in claim 2, wherein said multi-ple lis one. v

4. Means as defined in claim 2, wherein the operative connections between the rotor and the` means which electrifies the commutation elements in the cycle 'of progress includes means to change the angular position of said respect to the rotor; f

55. Means as defined in claim 2, wherein the commuta-y tion elements comprise oommutator bars, and wherein the means to electrify the commutation ele-ments in said cycle of progress comprises at least one brush andmeans to support the same for cyclic movement with respect to the commutator ba-rs, and wherein the operative connections between the rotor and the means which electrities the commutation elements in said cycle of progress comprises a driving connection between the rmotor` and lsaid brush. f

6. In an electric motor, 'the combination of statorand lrotor elements, means to journal said elements co-axially with respect to each other, the stator element including a plurality of sections not less than three spaced in succession laxially of the motor, each stator element including a plurality of stator poles spaced equidistant around the -axis of the motor and at the same radius from said axis, the rotor element including a plurality of sections equal lto the number of stator sections, each rotor section including a plurality of fteeth spaced equidistantv around the axis of the motor and at the same radius from said axis, the number of rotor teeth of each ysection vbeing equal `15 to the number of stator poles of such section, the teeth of each rotor being simultaneously in Ituill registryv with the poles of the companion stator section for each angular advance of the rotor equal to 360 divided by the number of rotor teeth of such section, and the teeth of the several rotor sections being successively in full registry with the poles of the companion stator sections with progress of such full registry of the rotor teeth and companion stator poles of the sections in successive cycles of such full registry conditions of the sections, magnetizing coils for the several sections, each coil when energized generating a magnetomotive force producing flux o-w between all of the poles of the lcorresponding stator section and all of the teeth of such rotor section, together with commutation means to electrically energize the magnetizing `coils in succession, said commutation means including a iirst deiined current conductor in connection with each stator coil, a series of second defined current supply connections equal in number to the number of stator coils, a group of movable rst defined current conductor electrifying elements for each first defined current conductor, each such group including a number conductor electrifying means equal to the number of stator coils,

.separate current supply connections between the movable current conductor electrifying elements of each group and the second dened current supply connections, operative control connections between the rotor and all of said Tconductor electrifying means of said groups effectively to yof the groups in successive phase relationship such that hthe first defined current conductor for each stator coil is 1n electrifying connection with each of the second defined current supply connections sequentially during rotor tooth `movement between successive stator poles, and being such lthat Ilthe rlirst deiined current conductors for Iall of 'the stator coils are individually in electri-fying connection with separate ones of the second deiined current supply connections, together with switching means to selecy'tively supply current to the second deiined current supply connections,

7. Means to accelerate a body having a large mass to dn've said body at a pre-determined speed, said means including an electric motor having stator and rotor elements, means to journal said elements coaxial1y with respect to each other, the stator element including a plurality of sections spaced in succession axially of the -motor, each stator element including -a plurality of stator poles spaced equidistant yaround the axis of the motor and at the same radius from said axis, the rotor element including a plurality of sections equal to the number of stator sections, each rotor section including a plurality of teeth spaced equidistant around the axis of the motor -and at the same radius from said axis, the number of rotor teeth of each section ybeing equal t the number lot stator poles of such section, the teeth of each rotor section being simultaneously in full registry with the poles of the companion stator section `for each angular yadvance of the rotor equalto 360 divided by the number of rotor teeth of such section, and the teeth of the several rotor sections being successively `in full registry with the poles of the companion stator sections with progress of suchfull registry of the rotor teeth and companion stator lpoles of the sections in `successive cycles of such yfull registry conditions of the sections, magnetizing coils for .the several sections, each coil when energized generating a magnetomotive force producing ilux flow between all of ,the poles of the correspondingA stator section and all of the teeth of such rotor section, a driving element in between the rotor of the motor and said driving element, said driving connections including a flexible coupling having an input element, an output element, and a fexible element connecting said input and output elements, a driving connection between the rotor and the input element vof the coupling, a driving connection between the output element of the coupling, `and means to supply current to the magnetizing coils of the stator in a progressive sequence to produce a succession of driving impulses of the rotor shatit and the input element of the coupling ywith yield of the ilexible element, said driving impulses being in the same direction of drive.

S. Means as defined in claim 7, wherein the means which supplies current to the magnetizing coils of the stator is constituted to deliver the current to the coils individually and in said progressive sequence.

9. Means as delined in claim 8, wherein the supply of current to each coil in such sequence terminates not later than the commencement of supply of current to the next coil of the sequence.

10. Means as defined in claim 8, wherein the supply of current to each coil in such sequence terminates before the commencement of supply of current to the next coil of the sequence. Y

11. Means as defined in claim 8, wherein the supply of current Ito each coil in such sequence terminates after the commencement of supply of current to the next coil of the sequence.

l2. The combination of a stepping motor and means to improve the accuracy of operation of said motor, comprising an electric motor having stator and rotor elements, means to journal said elements co-axially with respect to each other, the stator element including a plurality of sections spaced in succession axially of the motor, each stator element including a plurality of stator poles spaced equidistant around the axis of the motor and at the same radius from said axis, the rotor element including a plurality of sections equal to the number of stator sections, each rotor section including a plurality of teeth spaced equidistant around the axis of the motor and at the same radius from said axis, the number of rotor teeth of each section being equal to the number of stator poles of such section, the teeth of each rotor section being simultaneously in full registry with the poles of the companion stator section for each angular advance of the rotor equal to 360 divided by the number of rotor `teeth of such section, and the teeth of the several rotor sections being successively in full registry with the poles of the companion stator sections with progress of such full registry of the rotor teeth and companion stator poles of the sections in successive cycles of such full registry conditions of the sections, magnetizing coils for the several sections each coil when energized generating a magnetomotive force producing ux flow between al1 of the -rotor` element, av drag torque producing element in connection with the rotor element, and means to adjust the drag torque of such drag torque element.

13. Means as defined in claim l2, wherein said succession of current supply to the magnetizing coils includes reversals of the order of progress of such succession of driving impulses. Y A

14. Means as defined in claim 12, wherein said succession of current supply to the magnetizing coils produces a continuous succession of unidirectional driving impulses.

'15. In an electric motor, the combination of stator and rotor elements, means to journal said elements co-aXally with respect to each other, the stator element including a plurality of sections spaced in succession axially of the motor, each .stator element including a plurality of stator and at the same radius from said axis, the rotor element including a plurality of sections equal tothe number of stator sections, each rotor section including a plurality of teeth spaced equidistant around the axis of the motor and at the same radius from said axis, the number of rotor teeth of each section being equal to the number of stator poles of such section, the teeth of each rotor rsection being simultaneously in full registry with the poles of the companion stator section for each angular advance of the rotor equal to 360 divided by the number of rotor teeth of such section, and the teeth of the several rotor sections being successively in full registry with the poles of the companion stator sections with progress of such full registry of the rotor teeth and companion stator poles of the sections in successive cycles of such full registry conditions of the sections, magnetizing coils for the several sections, each coil when energized generating a magnetomotive force producing flux flow between all of the poles of the corresponding stator section and al1 of the teeth of such rotor section, together with means to deliver electrical impulses to the magnetizing coils, the teeth of each rotor section comprising at least one block of sintered nely granular magnetic material highly compacted by large pressures'.

16. In an electric motor, the combination of stator and rotor elements, means to journal said elements co-axially with respect to each other, the stator element including a plurality of sections spaced in succession axially of the motor, each stator element including a plurality of stator poles spaced equidistant around the axis of the motor and at ythe same radius from said axis, the rotor element including a plurality of sections equal to the number of stator sections,each rotor section including a plurality of teeth spaced equidistant around the axis of the motor and at the same radius from said axis, the number of rotor teeth of each section being equal to the number of stator poles of such section, the teeth of each rotor section being simultaneously in full registry with the poles of the companion stator section for each angular advance of the rotor equal to 360 divided by the number of rotor teeth of such section, and the teeth of the several rotor sections ybeing successively in full registry with the poles of the companion stator sections with progress of such full registry of the rotor teeth and companion stator poles of the sections in successive cycles of such full registry conditions for the sections-magnetizing coils for the several sections, each coil when energized generating a magnetomotive force producing ux ow between all of the poles of the corresponding stator section and all of the teeth of such rotor section, together with means to deliver electrical impulses to the magnetizing coils, the poles of each stator section comprising at least one block of sintered iinely granular magnetic vmaterial. highly compacted by large pressure.

References Cited in the file of this patent UNITED STATES PATENTS 166,431 Tittman Aug. 3, 1875 1,275,665 Eichbaum Aug. 13, 1918 1,353,025 Chicken et al. Sept. 14, 1920 1,440,729 French Ian. 2, 1923 1,850,598 Mills et al Mar. 22, 1932 2,066,343 Gillen Jan. 5, 1937 2,343,325 Ranseen Mar. 7, 1944 2,555,097 Rotureau May 29, 1951 

